Cook pasta in a large saucepan of salted boiling water following packet directions. Drain. Set aside.
Place salmon in a large bowl. Add cajun seasoning. Toss to coat. Season with salt. Set aside.
Heat oil in a large frying pan over medium heat. Place salmon pieces in a single layer. Cook for 2 minutes on each side. Remove from pan. Set aside.
Meanwhile heat butter in the same pan over medium-high heat.
Add onions and garlic. Saute, stirring occasionally, for 2-3 minutes or until soft and translucent.
Add cream and dried oregano. Season with salt and pepper. Stir to combine. Simmer for about 5-6 minutes.
Add grated parmesan and parsley. Stir. Simmer for a minute.
Stir in cooked pasta and salmon.